Fastening structure using a taper implant

ABSTRACT

A fastener structure for fastening a first member and a second member using a taper implant having a threaded hole therein. The taper implant has a frusto-conical outer surface, a projecting portion connected to a larger diameter end and a threaded hole passing therethrough. The first member has a wall portion with a tapered hole extending therethrough and a counterbored portion adjacent a larger diameter end to receive the projection portion of the taper implant. The taper implant is inserted into the hole of the first member and held therein by frictional contact. The second member has a wall portion with a hole therethrough. The second member is positioned in contact with the first member and the two members are fastened together by inserting a male screw through the hole of the second member and threading the male screw into engagement with the threaded hole of the taper implant.

This is a continuation application of U.S. Ser. No. 09/984,763, filedOct. 31, 2001, which is a divisional application of U.S. Ser. No.08/803,232 filed Feb. 20, 1997 now U.S. Pat. No. 6,488,458.

BACKGROUND OF THE INVENTION

The present invention relates to a taper implant, a screw-fasteningstructure using a taper implant with female threads, a forming drill fordrilling an insertion hole for the taper implant, and a hammer fordriving the taper implant.

Generally, often inserted or press-fitted into a soft base member, suchas an aluminum plate, are those other members which are harder than thebase member and have an axis perpendicular to the surface of the basemember. For example, when female threads are tapped in an aluminum plateand this aluminum plate is fastened to another plate by using a malestainless screw, chips are generated and fallen from the aluminum femalethreads upon the male screw being tightened into a hole with the femalethreads in the aluminum plate. If a falling of chips is not desired as,e.g., in the assembly step of electronic devices and units, areinforcing member is often inserted into the hole with the femalethreads in the aluminum plate. Such a reinforcing member is in the formof a coil spring made of stainless steel having strength comparable tothe male screw and being rhombic in cross-section. The reinforcingmember is inserted into a threaded hole tapped beforehand to be fit withan outer periphery of the reinforcing member, and a male screw isinserted into the threaded hole along an inner periphery of thereinforcing member. The use of the reinforcing member preventsgeneration of chips because the male screw contacts the stainlessreinforcing member.

As another example, a stainless positioning pin is sometimespress-fitted into a hole drilled in an aluminum plate.

However, when a reinforcing member is inserted into a hole of analuminum plate, insertion of the reinforcing member requires a skill.More specifically, in the case of inserting the reinforcing member witha tool, while rotating it, into a threaded hole tapped to be fit with anouter periphery of the reinforcing member, the inserted reinforcingmember may skip some threads of the threaded hole, or it may deform intoa conical shape (as the reinforcing member is inserted, the innerdiameter of its lower portion is gradually reduced), unless the workeris skilled. This has raised the problem that the process of insertingthe reinforcing member is poor in working efficiency.

Also, when a stainless positioning pin is inserted into a hole of analuminum plate, the positioning pin may be inserted obliquely withrespect to the aluminum plate due to deformation of the aluminum plate,for example, unless the worker is skilled. This has raised the problemthat the process of inserting the positioning pin is poor in workingefficiency.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a taper implant, ascrew-fastening structure using a taper implant with female threads, aforming drill for drilling an insertion hole for the taper implant, anda hammer for driving the taper implant, each of which ensures goodworking efficiency.

To achieve the above object, a taper implant according to the presentinvention comprises a taper portion having an outer surface beingfrustconical in shape, and a projecting portion formed at an outermostend of the taper portion on the larger-diameter side to project outwardwith respect to the taper portion, and having a flat surface lyingperpendicularly to the axial direction of the taper portion. In apreferable form, the projecting portion is a disk-shaped flange portionwhich is uniformly projected outward from the outer surface of the taperportion. The taper implant further comprises a fit portion extending inthe axial direction of the taper portion. With such a construction, justby dropping the taper implant into a hole bored in one of members to befastened and having a hole taper portion, and then driving the taperimplant into the hole by hitting the side of the flange portion, thetaper portion and the flange portion are press-fitted to an inner wallsurface of the hole bored in the fastened member, enabling the taperimplant to be easily fixed to the fastened member, while the taperimplant is prevented from overly thrusting into the hole. As a result,the working efficiency is improved.

Also, to achieve the above object, in screw-fastening structure using ataper implant with female threads according to the present invention, ahole having a hole taper portion gradually spreading toward alarger-diameter opening is drilled in a first member, a taper implanthaving a taper portion including female threads tapped thereinbeforehand is fitted to the hole taper portion, and a male screw isinserted and tightened into the female threads from the side of a secondmember, whereby the first and second members are fastened to each other.With that structure, the work of fastening two members to each other canbe performed with high efficiency.

Further, to achieve the above object, in a forming drill for drilling aninsertion hole for a taper implant according to the present invention,the drill integrally includes a taper portion drilling bit for boring ahole into which a taper portion of the taper implant is to be inserted,and a step portion drilling bit for boring a hole into which aprojecting portion of the taper implant is to be inserted, and a holetaper portion and a hole step portion of the hole are drilled in amember at the same time by the integral bits of the drill. With such aconstruction, control of tight-fit accuracy of the taper implant can befacilitated.

In addition, to achieve the above object, a hammer for driving a taperimplant according to the present invention comprises a piston pushedforth by a compression spring, and opening/closing means for selectivelyopening and closing an exhaust port communicating an air chamber withthe outside, the exhaust port having a sectional area set larger than asectional area of an air supply port through which compressed air isintroduced to the air chamber, the piston being pushed back againstbiasing force of the compression spring by the compressed air introducedto the air chamber. With such a construction, the taper implant can bedriven under driving force so reduced as to prevent damage of thefastened member, and the piston can be automatically pushed back to itsstart position. As a result, the work of driving the taper implant canbe easily performed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view showing the conceptual structure ofa taper nut according to a first embodiment of the present invention.

FIG. 2 is an enlarged vertical sectional view showing the taper nutaccording to the first embodiment of the present invention.

FIG. 3 is a side view of a forming drill for use with the taper nutaccording to the first embodiment of the present invention.

FIG. 4 is an explanatory view of a hole bored by the forming drill shownin FIG. 3.

FIGS. 5A, 5B, 5C, 5D and 5E are representations of steps for explaininga screw-fastening structure of two fastened members using the taper nutaccording to the first embodiment of the present invention.

FIG. 6 is a partial sectional view of a hammer for driving the taper nutaccording to the first embodiment of the present invention.

FIG. 7 is a partial plan view of FIG. 6.

FIG. 8 is an explanatory view of a system for automatically driving thetaper nut according to the first embodiment of the present invention.

FIGS. 9A and 9B are explanatory representations of steps for drilling ahole by a second example of the forming drill for use with the taper nutaccording to the first embodiment of the present invention.

FIGS. 10A, 10B and 10C are representations of steps for explaining asecond example of the screw-fastening structure of two fastened membersusing the taper nut according to the first embodiment of the presentinvention.

FIG. 11 is a vertical sectional view of a taper nut according to asecond embodiment of the present invention.

FIG. 12 is an illustration for explaining joining forces developed bythe taper nut according to the second embodiment of the presentinvention.

FIG. 13 is a vertical sectional view of a taper nut according to a thirdembodiment of the present invention.

FIG. 14 is a vertical sectional view of a taper nut according to afourth embodiment of the present invention.

FIG. 15 is a vertical sectional view of a taper nut according to a fifthembodiment of the present invention.

FIG. 16 is a side view, partly vertically sectioned, of a reference pinaccording to a sixth embodiment of the present invention.

FIG. 17 is a partial vertical sectional view showing the reference pin,in its driven state, according to the sixth embodiment of the presentinvention,

FIG. 18 is a partial vertical sectional view showing a taper implantwith a positioning hole, in its driven state, according to a seventhembodiment of the present invention.

FIGS. 19A, 19B and 19C are representations for explaining a process forpositioning two base members by using both a taper implant with apositioning pin according to the sixth embodiment of the presentinvention and the taper implant with a positioning hole according to theseventh embodiment of the present invention.

FIGS. 20A and 20B are partial vertical sectional views for explaining amanner of changing tolerance of the positioning hole formed in the taperimplant with a positioning hole according to the seventh embodiment ofthe present invention.

FIG. 21 is a partial vertical sectional view showing a reference pin, inits joined state, according to an eighth embodiment of the presentinvention.

FIG. 22 is a partial vertical sectional view showing a reference pin, inits driven state, according to a ninth embodiment of the presentinvention.

FIG. 23 is a partial vertical sectional view showing a reference pin, inits driven state, according to a tenth embodiment of the presentinvention.

FIG. 24 is a partial vertical sectional view showing a reference pin, inits driven state, according to an eleventh embodiment of the presentinvention.

FIG. 25 is a partial vertical sectional view showing a reference pin, inits driven state, according to a twelfth embodiment of the presentinvention.

FIG. 26 is a partial vertical sectional view showing a reference pin, inits driven state, according to a thirteenth embodiment of the presentinvention.

FIGS. 27A and 27B are partial vertical sectional views showing steps ofdriving a taper implant with a guide bar according to a fourteenthembodiment of the present invention.

FIG. 28 is a partial vertical sectional view showing a taper implantwith a tension spring post, in its driven state, according to afifteenth embodiment of the present invention.

FIG. 29 is a partial vertical sectional view showing a taper implantwith a tension spring post, in its driven state, according to asixteenth embodiment of the present invention.

FIG. 30 is a partial vertical sectional view showing a taper implantwith a tension spring post, in its driven state, according to aseventeenth embodiment of the present invention.

FIG. 31 is a partial vertical sectional view showing a taper implantwith a tension spring post, in its driven state, according to aneighteenth embodiment of the present invention.

FIG. 32 is a partial vertical sectional view showing a taper implantwith a bearing post, in its driven state, according to a nineteenthembodiment of the present invention.

FIG. 33 is a partial vertical sectional view showing a taper implantwith a bearing post, in its driven state, according to a twentiethembodiment of the present invention.

FIG. 34 is a partial vertical sectional view showing a taper implantwith a stud bolt, in its driven state, according to a twenty-firstembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A taper nut as one example of a taper implant with female threadsaccording to a first embodiment of the present invention will bedescribed below with reference to FIGS. 1 to 10.

In FIG. 1, a taper nut 1 as one example of the taper implant with femalethreads according to this embodiment comprises a taper portion 101 and aflange or projecting portion 102. The taper portion 101 has an outersurface being frusto-conical in shape. The flange portion 102 is formedat an outermost end of the taper portion 101 on the larger-diameterside. A lower surface 103 of the flange portion 102 is extendedperpendicularly to the axial direction of the taper portion 101.

Further, female threads 104 are tapped through the taper nut 1beforehand. The female threads 104 have an axis aligned with the axis ofthe taper portion 101. In other words, the female threads 104 serve as acoaxial fit portion extending in the axial direction of the taperportion 101.

In use, as described later, the taper nut 1 is implanted into a holeformed in a soft base member. When the soft base member is made ofaluminum, the taper nut 1 is fabricated of stainless steel. Thus, thetaper nut 1 implanted in a base member is generally fabricated ofmaterials harder than the base member. The taper nut 1 is employed tofasten two plates to each other in combination with a male screw. Onefirst plate in which the taper nut 1 is implanted and the other secondplate are fastened together by inserting the male screw into a holeformed in the second plate and then screwing it into the female threads104 formed in the taper nut 1.

The first plate is, e.g., a backboard frame made of aluminum fixedlymounted in a housing of a universal computer. The second plate is, e.g.,a printed-board fixedly fastened onto the backboard frame. By way ofexample, the backboard frame has overall dimensions of 800 mm×600 mm, athickness of 15 mm, and weight of about 8 kg. The printed board hasoverall dimensions of 760 mm×560 mm and weight of about 30 kg in acondition that logical devices such as CPU and storage devices such asmemories are mounted on its surface. When those backboard frame andprinted board are fastened to each other with a pair of theabove-mentioned taper nut 1 and a male screw, both the members can befirmly fastened together by using 70 pairs of the taper nuts 1 and themale screws.

Here, it is assumed that the outer diameter of the male screw put intothe female threads is d0, the maximum diameter of the taper portion 101at its end on the larger-diameter side is d1, the outer diameter of theflange portion 102 is d2, and the width of the flange portion 102 is d3.It is also assumed that the length of the taper nut 1 is L and thethickness of the flange portion 102 is t.

Actual size and shape of the taper nut according to the first embodimentof the present invention, which was fabricated corresponding to a malescrew of type M4, will now be described with reference to FIG. 2. Notethat FIG. 2 shows the actual taper nut enlarged five times. Also, thesame reference numerals as in FIG. 1 denote the same portions.

In FIG. 2, a male screw put into the female threads tapped through thetaper nut 1 is of type M4 and the outer diameter d0 thereof is 4 mm.Correspondingly, dimensions of the taper nut 1 are set as follows. Themaximum diameter d1 of the taper portion 101 is 6 mm, the outer diameterd2 of the flange portion 102 is 8 mm, and the width d3 of the flangeportion 102 is 1 mm. Also, the length L of the taper nut 1 is 8 mm andthe thickness t of the flange portion 102 is 1 mm. Furthermore, thetaper portion 101 has a taper rate of 1/20.

A forming drill for boring a hole in which the taper nut as one exampleof the taper implant with female threads according to the firstembodiment of the present invention is to be implanted, and theconfiguration of a hole bored in a base member by the forming drill willnow be described with reference to FIGS. 3 and 4.

A forming drill 2 as one example of drilling tools, shown in FIG. 3,integrally includes a taper portion drilling bit 201 for boring a holeinto which the taper portion 101 of the taper nut 1 is to be inserted,and a step portion drilling bit 202 for boring a hole into which theflange portion 102 of the taper nut 1 is to be inserted, both the bits201, 202. The forming drill 2 further includes a guide hole drilling bit203 for boring a guide hole to guide the male screw when it is inserted,and a hole end deburring bit 204 for removing burrs at an uppermost edgeof the bored hole. The guide hole drilling bit 203 has an outer diameterlarger than the outer diameter of the male screw inserted. The guidehole drilling bit 203 and the hole end deburring bit 204 are required tobe adjusted in length and position depending on the thickness of a plateto be fastened.

The forming drill 2 can simply bore a fit hole with high precision byattaching it to a drilling machine, for example, and operating themachine for drilling. It is needless to say that if a machining centerhaving high rigidity is employed, the precision is further improved.

The configuration of the hole bored by the forming drill 2 shown in FIG.3 will now be described with reference to FIG. 4.

A first member 4 to be fastened is a plate made of an aluminum alloy. Ahole 3 is bored in the fastened member 4 by the forming drill 2. Thehole 3 comprises a hole taper portion 301 bored by the taper portiondrilling bit 201 of the forming drill 2, a hole step portion 302 boredby the step portion drilling bit 202, a male screw guide portion 303bored by the guide hole drilling bit 203, and a hole end chamferedportion 304 formed by the hole end deburring bit 204.

The depth of the hole step portion 302 is not under any restrictions,but may be optionally selected to be deep or shallow depending on thefastening structure used. In this embodiment, it is important to drillthe hole taper portion 301 and the hole step portion 302 at the sametime for the reason described later.

Steps of screwing two fastened members by using the taper nut accordingto the first embodiment of the present invention will now be describedwith reference to FIGS. 5A-5E.

As shown in FIG. 5A, a hole into which the taper nut is to be fitted isbored in the fastened member 4 made of an aluminum alloy by using theforming drill 2.

With the drilling shown in FIG. 5A, the hole 3 is bored in the fastenedmember 4 as shown in FIG. 5B. As described above in connection with FIG.4, the hole 3 comprises the hole taper portion 301, the hole stepportion 302, the male screw guide portion 303, and the hole endchamfered portion 304. The taper nut 1 made of stainless steel is fittedinto the hole 3. As described above in connection with FIG. 1 or 2, thetaper nut 1 comprises the taper portion 101, the flange portion 102, andthe female threads 104.

The taper portion 101 of the taper nut 1 is so sized as to lightlytight-fit into the hole taper portion 301 of the hole 3 when fitted.Specifically, as shown in FIG. 5C, in a state of the taper nut 1 beingsimply dropped into the hole 3, the lower surface 103 of the flangeportion 102 is floated from the hole step portion 302 of the hole 3.Here, an amount F by which the lower surface 103 of the flange portion102 is floated from the hole step portion 302 of the hole 3 will bereferred to as a tight-fit allowance.

By hitting an upper surface of the flange portion 102 of the taper nut 1in the state shown in FIG. 5C, the taper nut 1 is driven into the hole 3of the fastened member 4 and then stopped when the flange portion 102comes into abutment against the hole step portion 302.

Since the hole taper portion 301 of the hole 3 and the taper portion 101of the taper nut 1 engage each other, the axis of the hole 3 and theaxis of the taper nut 1 are aligned with each other. By forming the hole3 in rectangular relation to the surface of the fastened member 4,therefore, the axis of the taper nut 1 also lies perpendicularly to thesurface of the fastened member 4. Thus, by tapping the female threads104 through the taper nut 1 to have an axis aligned with the axis of thetaper portion 101 of the taper nut 1, it is possible to easily positionthe axis of the female threads 104 in rectangular relation to thesurface of the fastened member 4.

Further, with the flange portion 102 provided at the top of the tapernut 1, the taper nut 1 is surely stopped upon the lower surface 103 ofthe flange portion 102 of the taper nut 1 abutting against the hole stepportion 302 of the hole 3. If the flange portion 102 is not provided,the taper nut 1 would be thrust into the hole 3 and the hole 3 of thefastened member 4 would be greatly deformed because the fastened member4 made of an aluminum alloy is softer than the taper nut 1 made ofstainless steel. By contrast, with the flange portion 102 provided onthe taper nut 1 in this embodiment, it is possible to prevent the tapernut 1 from overly thrusting into the hole 3 and hence prevent the hole 3from deforming.

In a state shown in FIG. 5D, because the taper nut 1 is fixedly held onthe fastened member 4 by frictional forces, the tight-fit allowance F ofthe taper nut 1 for the hole 3 is required to be controlled with goodprecision. To this end, it is important to not only drill the taperportion 101 of the taper nut 1 with good precision, but also drill thehole taper portion 301 and the hole step portion 302 of the hole 3 atthe same time. The tight-fit precision of the taper nut is determined bythe precision of two bits of the forming drill 2, i.e., the taperportion drilling bit 201 and the step portion drilling bit 202, fordrilling both the hole taper portion 301 and the hole step portion 302at the same time. In other words, because the taper nut 1 is advancedwhile spreading the hole 3 in the course of being driven and thenstopped upon contact of the flange portion 102 of the taper nut 1 withthe hole step portion 302 of the hole 3, the hole taper portion 301 andthe hole step portion 302 of the hole 3 must be drilled with highprecision.

For achieving a stable fastening structure, it is also important tocontrol the tight-fit allowance F of the taper nut 1 for the hole 3 withhigh precision. Taking as an example the taper nut fabricatedcorresponding to a male screw of type M4, which has been described abovein connection with FIG. 2, the maximum diameter d1 of the taper portion101 is 6 mm and the tolerance range of actual dimension is set to spanfrom +0.02 mm to +0.04 mm. Thus, the average tolerance is +0.03 mm. Onthe other hand, the maximum diameter of the taper portion drilling bit201 of the forming drill 2, shown in FIG. 3, for boring the taperportion 101 of the taper nut 1 is 6 mm and the tolerance range of actualdimension is set to span from −0.01 mm to +0 mm. Thus, the averagetolerance is −0.005 mm. In other words, the precision is controlled suchthat the maximum diameter of the hole taper portion 301 of the hole 3bored by the taper portion drilling bit 201 is 0.035 mm larger than themaximum diameter of the taper portion 101 of the taper nut 1. Further,the taper rate of the taper portion drilling bit 201 of the formingdrill 2 and the taper rate of the taper portion 101 of the taper nut 1are both set equal to 1/20. The tight-fit allowance F of 0.7 mm (=0.035mm×20) is thereby resulted. Consequently, the tight-fit allowance F ofthe taper nut 1 for the hole 3 can be controlled with good precision bydrilling the taper portion 101 of the taper nut 1 accurately anddrilling both the hole taper portion 301 and the hole step portion 302of the hole 3 at the same time.

Next, as shown in FIG. 5E, when a second fastened member 5 having a hole501 bored therethrough is fastened to the first fastened member 4, thesecond fastened member 5 is placed adjacent the rear side of the firstfastened member 4 into which the taper nut 1 has been implanted, and thetwo members are tightly joined together by using a male screw 6. In thecase of the first fastened member 4 being made of an aluminum alloy, thesecond fastened member 5 is, e.g., a printed board on which circuitdevices are mounted. Since the male screw 6 imposes a load on the taperunit 1 in the direction to tighten the taper-fit, there is no risk thatthe taper nut 1 may be loosened from the first fastened member 4. Also,if desired, the taper nut 1 can be simply removed from the hole taperportion 301 of the hole 3 just by lightly hitting the head of the malescrew 6 in a state that the male screw 6 is loosened.

As a test experiment, the taper nut 1 corresponding to a male screw oftype M4 was fabricated of stainless steel, and the first fastened member4 was fabricated of an aluminum alloy. A condition of the taper nut 1driven into the first fastened member 4 was examined by setting thetaper rate of each of the two parts to 1/20 and variously changing themaximum diameter d1 of the taper portion 101 of the taper nut 1 to varythe tight-fit allowance of the taper portion 101. As a result, it wasconfirmed that although the tight-fit allowance of the taper portion 101was changed in the range of 0.01 to 0.07 mm, the taper nut 1 could beeasily driven into the first fastened member 4 and fixedly held therewith satisfactory tightness without causing any rotation. From a test ofturning the male screw into taper nut 1, it was also confirmed that thetaper nut 1 developed no rotation and two fastened members could befirmly fastened together.

The taper rate is the most important parameter in the present invention.To ensure that the taper nut is not only easily driven, but also held ina driven state with good reliability, the taper angle must be at leastsmaller than the friction angle. From the viewpoints of easiness indriving and reliability in maintaining of the driven state, it wasconfirmed that the taper rate of 1/20 was an optimum value. But, thetaper rate in the range of 1/50 to 1/10 also showed preferable resultsfrom the practical point of view. Further, the taper rate in the rangeof 1/7 to 1/6 was also found applicable without problems. However, thegreater driving force is required as the taper rate increases, and thereoccurred a phenomenon that the driven taper nut sprang out from thehole, when the taper rate exceeded 1/6.

The present invention is not limited to the use of a male screw of typeM4, but can be applied to male screws of types M2 to M10 as well.Preferable dimensions of taper nuts employed in combination with thosemale screws are as follows.

Assuming that the outer diameter (mm) of the male screw is d0, themaximum diameter d1 of the taper portion 101 of the taper nut 1 ispreferably in the range of:

d1=(1.1˜2.0)×d0

A more preferable range of d1 is given by:

d1=(1.1˜1.5)×d0

The outer diameter d2 of the flange portion 102 of the taper nut 1 ispreferably in the range of:

d2=d0+(0.5˜3.0)

The thickness t of the flange portion 102 of the taper nut 1 ispreferably in the range of:

t=0.5˜3 mm

The taper rate of the taper portion 101 is, as stated above, preferablyin the range of:

taper rate=1/50˜1/10

The overall length L of the taper nut 1 is preferably in the range of:

L=(1˜3)×d0

The tight-fit allowance F of the taper portion 101 is, in relation tothe maximum diameter d1 of the taper portion 101, preferably in therange of:

F=(2˜20%)×d1

The values mentioned above are applied to the case of fastening membersmade of soft metal (such as an aluminum alloy or pure copper). If softermaterials (such as wood or plastics) are employed, it is advantageousthat the taper rate is set to a relatively large value in the range of1/30 to 1/5 and the width d3 of the flange portion 102 is also set to arelatively large value in the range of 1 to 4 mm. By so setting thetaper rate and the flange width to relatively large values, when twofastened members made of those softer materials are fastened to eachother by using the taper nut and a male screw, the taper nut can beprevented from biting into the fastened member.

While the taper nut is made of stainless steel in the illustratedembodiment, materials of the taper nut are not limited to stainlesssteel, but may be selected from a variety of materials which are harderthan the fastened member. In combination with an aluminum alloy orcopper, steel (such as SS steel, carbon steel, slightly alloyed steel,or refined steel (hardened and tempered to HRC of about 15 to 25), forexample, is also employed in addition to stainless steel. As nonferrousmaterials, phosphor bronze, brass, etc. are preferably used.

When the fastened member is made of wood, plastics, aluminum or the likecan be used as materials of the taper nut. When the fastened member ismade of plastics, aluminum, stainless steel, steel, phosphor bronze,brass or the like can be used as materials of the taper nut. When thefastened member is made of steel, hardened steel (super steel) can beused as materials of the taper nut.

Further, materials of the taper nut is not always required to be harderthan materials of the fastened member, but may be comparable in hardnessto the fastened member. In other words, when the fastened member is madeof steel, steel can be used as materials of the taper nut.

Additionally, for the fastened member made of highly hard materials,such as a metal mold, the taper nut made of materials softer than thebase member may be used in consideration of friction, breakage andreplacement.

As described above, since the taper nut 1 having the female threads 104can be fixedly implanted into the fastened member 4 with ease just bydropping the taper nut 1 into the hole 3 of the fastened member 4,having the hole taper portion 301, and hitting the taper nut 1 from theside of flange portion 102, the working efficiency is improved.

Also, with the engagement between the taper portion 101 of the taper nut1 and the hole taper portion 301 of the hole 3, the female threads 104tapped through the taper nut 1 are easily prevented from offsetting fromcoaxial relation to the hole 3 of the fastened member 4.

Further, since the flange portion 102 is provided at the top of thetaper nut 1, the taper nut 1 is stopped when the lower surface 103 ofthe flange portion 102 of the taper nut 1 comes into abutment againstthe hole step portion 302 of the hole 3. Accordingly, by controlling thetight-fit allowance F defined as an amount by which the flange portion102 of the taper nut 1 is floated from the hole step portion 302 of thehole 3 in a state that the taper nut 1 is dropped into the hole 3, it ispossible to keep constant an amount by which the taper nut 1 is driveninto the hole 3, frictional forces between the hole 3 and the taper nut1, and hence fixing force to hold the taper nut in the hole.

Moreover, in this embodiment, since the hole taper portion 301 and thehole step portion 302 of the hole 3 are bored by using the forming drill2 which include the taper portion drilling bit 201 and the step portiondrilling bit 202, control of the tight-fit allowance is facilitated.

Also, with the flange portion 102 provided at the top of the taper nut1, the taper nut 1 is surely stopped upon the lower surface 103 of theflange portion 102 of the taper nut 1 abutting against the hole stepportion 302 of the hole 3. If the flange portion 102 is not provided,the taper nut 1 would be thrust into the hole 3 and the hole 3 of thefastened member 4 would be greatly deformed because the fastened member4 made of an aluminum alloy is softer than the taper nut 1 made ofstainless steel. By contrast, with the flange portion 102 provided inthe taper nut 1 in this embodiment, it is possible to prevent the tapernut 1 from overly thrusting into the hole 3 and hence prevent the hole 3from deforming.

In addition, since the taper nut 1 and the nut 3 can be disengaged fromeach other by applying force to the taper nut 1 from thesmaller-diameter side of the taper portion 101, i.e., by hitting thehead of the male screw 6 engaged with the female threads 104, afterloosening the male screw 6 to some extent, the taper nut 1 can be easilyattached and detached.

Accordingly, the taper nut 1 can be easily replaced even when it isemployed under situations where the female threads are much susceptibleto wear or damage.

When the fastened member is discarded, it is possible to discard thefastened member and the taper nut, which are made of differentmaterials, separately from each other. This contributes to protection ofenvironment.

Since the removed taper nut can be reused, effective use of resources ispromoted.

The conventional method of inserting a reinforcing member into a holebored in a fastened member was not adaptable for small male screws oftypes M1 to M3 because the hole diameter is too small. By contrast, thisembodiment can be applied to those small male screws as well because itis only required to tap female threads through the taper nutcorresponding to any of the male screws of types M1 to M3.

The construction of a driving hammer for driving the taper nut of thisembodiment into the hole bored in the fastened member will now bedescribed with reference to FIGS. 6 and 7.

A driving hammer 7 is of hand-held type constructed such that thedriving force of the driving hammer 7 is generated by a spring and,after completion of a driving stroke, air force is utilized as power tocompress the spring.

The general structure of the driving hammer 7 will be first describedwith reference to FIG. 6.

A body 701 of the driving hammer 7 is cylindrical in shape and sized soas to enable the worker to grip it by the hand. Within an inner space ofthe body 701, a piston 702 is held to be vertically movable in adirection of arrow A. A lower rod 703 of the piston 702 is projectedoutward through a hole penetrating a bottom wall of the body 701, andhas a tip used for hitting the taper nut. A notch 705 is formed in anupper rod 704 of the piston 702 approximately near the middle thereof.When the piston 702 is moved upward, the notch 705 comes into engagementwith a movable block 707 provided at a fore end of a stopper 706,thereby stopping vertical movement of the piston 702. The movable block707 is biased by a compression spring 708 in a direction of arrow B.Also, as shown in FIG. 7, a V-shaped slot 709 is formed in a fore end ofthe movable block 707. With the notch 705 of the piston 702 engaging theV-shaped groove 709, the vertical movement of the piston 702 is stopped.

A plurality of exhaust ports 710 are formed through the bottom wall ofthe body 701. Within an air chamber 711 defined below the piston 702inside the body 701, there is disposed a spacer 712 slidably in adirection of arrow C. A plurality of exhaust ports 713 are formedthrough the spacer 712. By sliding the spacer 712 in the direction ofarrow C, communication between the exhaust ports 710 of the body 701 andthe exhaust ports 713 of the spacer 712 is selectively established andcut off.

The spacer 712 is slid by manually operating a switch 714 provided atthe top of the body 701. The switch 714 and the spacer 712 are connectedto each other through a lever 715. Therefore, when the switch 714 isoperated to move in a direction of arrow D, the spacer 712 is slid tothe left to establish the communication between the exhaust ports 710 ofthe body 701 and the exhaust ports 713 of the spacer 712.Simultaneously, with the movement of the switch 714 in the direction ofarrow D, a right end of the switch 714 engages an left edge of theV-shaped slot 709 of the movable block 707, whereupon the movable block707 is moved to the right to disengage the V-shaped slot 709 from thenotch 705.

A coil spring 716 is disposed between the lever 715 and the body 701.Accordingly, when the switch 714 is released from the worker's hand, thelever 716 is turned in a direction of arrow E to slide the spacer 712 tothe right, thereby cutting off the communication between the exhaustports 710 of the body 701 and the exhaust ports 713 of the spacer 712.

A compression spring 17 is disposed between an upper surface of thepiston 702 and an upper wall surface defining an inner space of the body701. The compression spring 17 biases the piston in a direction of arrowF.

Further, compressed air is introduced through an air supply port 718 tothe air chamber 711 in the body 701. An O-ring 719 is fitted over anouter periphery of the piston 702 to prevent the compressed air in theair chamber 718 from leaking upward from there.

The operation of the driving hammer 7 according to this embodiment willnow be described. In an illustrated state, the exhaust ports 710 of thebody 701 and the exhaust ports 713 of the spacer 712 are notcommunicated with each other. Therefore, when the compressed air isintroduced through the air supply port 718, the piston 702 is raised ina direction of arrow G against the biasing force of the compressionspring 717. At the same time, the upper rod 704 of the piston 202 isalso raised, causing the notch 705 of the upper rod 704 to engage theV-shaped slot 709 of the movable block 707.

When driving the taper nut with the driving hammer 7, the worker gripsthe switch by the hand to operate it. The gripping force moves theswitch 714 in the direction of arrow D and also slides the spacer 712 tothe left through the lever 15 to establish the communication between theexhaust ports 710 of the body 701 and the exhaust ports 713 of thespacer 712. As a result, the compressed air in the air chamber 711 isexhausted through the exhaust ports 713 of the spacer 712. Here, bysetting a total sectional area of the plurality of exhaust ports 710much larger than the sectional area of the air supply port 718, not onlythe compressed air in the air chamber 711 is quickly exhausted to theoutside, but also the compressed air introduced through the air supplyport 719 is exhausted through the exhaust ports 713. Accordingly, thepressure in the air chamber 711 falls down to almost the atmosphericpressure.

When the worker further slides the switch 714 in the direction of arrowD to such an extent that the right end of the switch 714 engages theleft edge of the V-shaped slot 709 of the movable block 707, whereuponthe movable block 707 is moved to the right to disengage the V-shapedslot 709 from the notch 705. Since the compression spring 717 is alwaysbiasing the piston 702, the piston 702 is now allowed to slide in thedirection of arrow F, causing the tip of the lower rod 703 to slidedownward. As a result, the taper can be driven by holding the tip of thelower rod 703 pressed against an upper surface of the taper nut.

When the worker releases the switch 14 from the hand after one stroke ofdriving the taper nut, the spacer 712 is slid to the right to cut offthe communication between the exhaust ports 710 of the body 701 and theexhaust ports 713 of the spacer 712. Accordingly, the compressed airintroduced through the air supply port 718 is accumulated in the airchamber 711 and raises the piston 701 in the direction of arrow Gagainst the biasing force of the compression spring 717. Then, the notch705 of the upper rod 704 engages the V-shaped groove 709 of the movableblock 707 to stop rising of the piston 702.

For each of cycles repeated as described above, it is possible to drivethe taper nut by utilizing the biasing force of the compression spring717 and, after that, to automatically raise the driving piston 702 toits initial position by utilizing the compressed air through the manualoperation of the switch 714.

Since the piston 702 is slid after exhausting the compressed air out ofthe air chamber 711, the driving force of the piston is determineddepending on the spring force of the compression spring 717. Therefore,the driving force of the piston is adjustable by changing the springforce of the compression spring 717.

If an air hammer or the like utilizing compressed air to produce drivingforce itself is employed as a hammer for driving the taper nut, in theform of a small part, of this embodiment, the driving force would be sostrong as to cause a hopping motion that the tip of the lower rod of thepiston is sprung back from the upper surface of the taper nut afterbeing hit against the upper surface of the taper nut. This leads to arisk that the lower rod of the piston hit against the fastened memberother than the taper nut, and the fastened member may be damaged. Bycontrast, in this embodiment wherein compression force of a spring isutilized as the force for driving the taper nut, the driving force canbe set to a value smaller than produced in the case of utilizing thecompressed air for driving. As a result, it is possible to preventdamage of the fastened member which would be otherwise caused due to theoccurrence of the above hopping motion.

Further, if the piston is manually raised against the biasing force ofthe compression spring, this manual operation would be hard to complete.In this embodiment, the operation of raising the piston can be easilymade because of utilizing the compressed air.

The entire construction of a system for automatically driving the tapernut according to this embodiment will now be described with reference toFIG. 8.

The process of driving each of several tens or more taper nuts into onefastened member in such a manner as described above can be efficientlyperformed by automating steps from supply to driving of the taper nuts.FIG. 8 shows the entire construction of an automatic driving systemadapted for that purpose.

A number of openings are formed in a conveyor 8 with certain intervalstherebetween. Taper nuts 1A, 1B, . . . , 1G, . . . are placed in theopenings of the conveyor 8 in random and carried in a direction of arrowH.

A posture determining sensor 9 is disposed below the conveyor 8 todetermine whether the taper nut 1 carried on the conveyor 8 is in aproper posture or not. The posture determining sensor 9 comprises, e.g.,a proximity sensor. For those taper nuts 1A, 1F, 1G which are insertedinto the opening of the conveyor 8 in the proper posture, since thedistance between the posture determining sensor 9 comprising theproximity sensor and the taper nut 1 is short, the proximity sensorissues an output signal indicating that the taper nut is in the properposture. On the contrary, for those taper nuts 1B, 1C, 1D, 1E which arenot properly inserted into the opening of the conveyor 8, since thedistance between the posture determining sensor 9 comprising theproximity sensor and the taper nut 1 is so long that the proximitysensor issues no output signal, based on which it can be determined thatthe taper nut is not in the proper posture.

An NG cylinder 10 is operated in accordance with a posture determinationsignal from the posture determining sensor 9. Specifically, if theposture of the taper nut placed on the conveyor 8 is not normal, the NGcylinder 10 receives an NG signal from the posture determining sensor 9and is operated at the timing when the relevant taper nut 1 is carriedto a position just above the NG cylinder 10, causing an end piston 1001to advance to remove each of the taper nuts 1B, 1C, 1D, 1E not in thenormal state from the conveyor 8.

A robot controller 11 controls the rotating operation of a robot 12 andthe operation of a vacuum suction head 14 of a suction cylinder 13attached to a tip of the robot 12. The robot controller 11 is operatedin accordance with the posture determination signal from the posturedetermining sensor 9. Specifically, if the posture of the taper nutplaced on the conveyor 8 is normal, the robot controller 11 receives anOK signal from the posture determining sensor 9 and operates the suctioncylinder at the timing when the relevant taper nut 1 is carried to aposition just below the vacuum suction head 14, thereby descending thevacuum suction head 14. After holding the taper nut 1 while sucking it,the vacuum suction head 14 is raised.

Then, the robot controller 11 operates the robot 12 to move the tapernut 1 to a position above the opening or hole of the fastened member 4.The fastened member 4 is rested on a table capable of moving in twodirections of X-Y so that a plurality of openings formed in the fastenedmember 4 beforehand can be each positioned just below the vacuum suctionhead 14 one after another. By releasing a vacuum state of the vacuumsuction head 14 when the taper nut 1 reaches a position just above theopening of the fastened member 4, the taper nut 1 is dropped into theopening. Here, the opening formed in the fastened member 4 has a holetaper portion as described above in connection with FIG. 4, whereas thetaper nut 1 has the taper portion in its outer periphery as describedabove in connection with FIG. 1. Therefore, by merely dropping the tapernut 1 above the opening, the taper nut 1 can be easily inserted into theopening of the fastened member 4 as shown in FIG. 5C. When the tapernuts are inserted into all of the openings formed in the fastened member4, the operation of inserting the taper nuts is completed.

Then, the fastened member 4 is transferred to a press-fitting station.In the press-fitting station, the fastened member 4 is rested on a tablecapable of moving in two directions of X-Y so that the plurality ofopenings formed in the fastened member 4 beforehand can be eachpositioned just below a piston 16 of a press-fitting cylinder 15 oneafter another. By operating the press-fitting cylinder 15 to descend thepiston 16, the taper nut 1 can be driven into the opening of thefastened member 4. When the taper nuts are press-fitted to all of theopenings formed in the fastened member 4, the operation of press-fittingthe taper nuts is completed.

In that way, a plurality of taper nuts can be easily driven into thefastened member by using the automatic driving system.

A second example of the forming drill for boring a hole, into which thetaper nut as one example of the taper implant with female threadsaccording to the first embodiment of the present invention is to beimplanted, will now be described with reference to FIGS. 9A-9B.

When the forming drill as one example of forming tools, described abovein connection with FIG. 3, is employed, a cutting load is so increasedthat the drill may chatter in a drilling machine with low transverserigidity. To avoid such a chattering, a forming drill 2′ having thestructure shown in FIGS. 9A-9B is employed.

First, as shown in FIG. 9A, a guide hole 303 for a male screw is boredthrough the fastened member 4 by using an ordinary drill 205.

Then, as shown in FIG. 9B, a fitting hole is bored by using the formingdrill 2′ having a guide portion 206 whose outer diameter is 0.05 to 0.15mm smaller than the diameter of the guide hole 303. In addition to theguide portion 206, as with the forming drill 2 shown in FIG. 3, theforming drill 2′ integrally includes a taper portion drilling bit 201for boring a hole into which the taper portion 101 of the taper nut 1 isto be inserted, and a step portion drilling bit 202 for boring a holeinto which the flange portion 102 of the taper nut 1 is to be inserted.The forming drill 2 further includes a hole end deburring bit 204 forremoving burrs at an uppermost end of the bored hole. The hole enddeburring bit 204 is required to be adjusted in length and positiondepending on the thickness of a plate to be fastened.

The hole bored by using the forming drill 2′ is the same as describedabove in connection with FIG. 4.

In the case of using the forming drill 2′ thus structured, since themale screw guide hole 303 is first bored in the fastened member 4 byusing the drill 205 and the forming drill 2′ is then employed to borethe hole while the guide portion 206 at its tip is inserted into theguide hole 303, it is possible to suppress vibration in the transversedirection and prevent the occurrence of chattering even if a drillingmachine with low transverse rigidity is used.

Steps of a second example for screwing two fastened members by using thetaper nut according to the first embodiment of the present inventionwill now be described with reference to FIGS. 10A-10C.

In the screw-fastening structure shown in FIG. 5, the second fastenedmember is fastened to the side of the first fastened member opposite tothe side where the taper portions of all the holes are opened. Bycontrast, in this example, the second fastened member is fastened to theside of the first fastened member where the taper portions of all theholes are opened.

As described above in connection with FIG. 5A, a hole into which thetaper nut is to be fitted is bored in the fastened member 4 made of analuminum alloy by using the forming drill 2. Thus, as shown in FIG. 10A,the hole 3 is bored in the fastened member 4 by drilling. The hole 3comprises the hole taper portion 301, the hole step portion 302, and themale screw guide portion 303. The taper nut 1 made of stainless steel isfitted into the hole 3. As described above in connection with FIG. 1 or2, the taper nut 1 comprises the taper portion 101, the flange portion102, and the female threads 104.

Here, the hole step portion 302 of the hole 3 is formed to have a depthsmaller than the thickness of the flange portion 102 of the taper nut 1.

The taper portion 101 of the taper nut 1 is so sized as to lightlytight-fit into the hole taper portion 301 of the hole 3 when fitted.

By hitting the upper surface of the flange portion 102 of the taper nut1 after inserting the taper nut 1 into the hole 3, the taper nut 1 isdriven into the hole 3 of the fastened member 4 and then stopped whenthe flange portion 102 comes into abutment against the hole step portion302, as shown in FIG. 10B. Also, in this state, the upper surface of theflange portion 102 of the taper nut 1 projects upward of the surface ofthe first fastened member 4.

Since the hole taper portion 301 of the hole 3 and the taper portion 101of the taper nut 1 engage each other, the axis of the hole 3 and theaxis of the taper nut 1 are aligned with each other. By forming the hole3 in rectangular relation to the surface of the fastened member 4,therefore, the axis of the taper nut 1 also lies perpendicularly to thesurface of the fastened member 4. Thus, by tapping the female threads104 through the taper nut 1 to have an axis aligned with the axis of thetaper portion 101 of the taper nut 1, it is possible to easily positionthe axis of the female threads 104 in rectangular relation to thesurface of the fastened member 4.

Further, with the flange portion 102 provided at the top of the tapernut 1, the taper nut 1 is surely stopped upon the lower surface 103 ofthe flange portion 102 of the taper nut 1 abutting against the hole stepportion 302 of the hole 3. If the flange portion 102 is not provided,the taper nut 1 would be thrust into the hole 3 and the hole 3 of thefastened member 4 would be greatly deformed because the fastened member4 made of an aluminum alloy is softer than the taper nut 1 made ofstainless steel. By contrast, with the flange portion 102 provided onthe taper nut 1 in this embodiment, it is possible to prevent the tapernut 1 from overly thrusting into the hole 3 and hence prevent the hole 3from deforming.

In the state shown in FIG. 10B, the taper nut 1 is fixedly held on thefastened member 4 by frictional forces.

Next, as shown in FIG. 10C, when a second fastened member 5 having ahole 501 bored therethrough is fastened to the first fastened member 4,the second fastened member 5 is placed adjacent the surface of the firstfastened member 4 into which the taper nut 1 has been implanted, and thetwo members are tightly joined together by using a male screw 6. In thecase of the first fastened member 4 being made of an aluminum alloy, thesecond fastened member 5 is, e.g., a printed board on which circuitdevices are mounted. Since the male screw 6 imposes a load on the taperunit 1 in the direction to tighten the taper-fit, there is no risk thatthe taper nut 1 may be loosened from the first fastened member 4.

The screw-fastening structure of this example has the strength (several10 kg even with a male screw of type M4) corresponding to the frictionalforces by which the driven taper nut is fixedly held in the hole. Toenhance the fastening strength in this example, it is effective toincrease the number of fastening points. Particularly, because thesecond fastened member 5 is floated from the first fastened member 4 dueto the taper nut 1 projecting from the surface of the first fastenedmember 4, the taper nut 1 is relatively easily susceptible to forceurging it upward in such a floating condition, and may be readilydislodged from the hole 3 if the two fastened members are fastenedtogether by using only one taper nut. That disadvantage can be preventedby using a plurality of, preferably, three or more, taper nuts. The useof plural taper nuts is also effective to determine a fixed plane andstabilize it.

It is also important to enlarge the tight-fit allowance. While thetight-fit allowance is set to range from 2 to 20% of the diameter of thetaper portion in the example shown in FIG. 5, a lower limit value ispreferably raised in this example to such an extent that the tight-fitallowance falls in the range of 4 to 20% thereof.

In this screw-fastening structure, if the hole step portion 302 of thehole 3 is set deeper than the thickness of the flange portion 102, thiswould not be preferable because force tending to withdraw the taper nutacts on it when the male screw 6 is tightened into the taper nut.Additionally, the male screw guide hole 303 shown in FIG. 10 is notalways required. But if the male screw guide hole 303 is bored wherepossible, this is advantageous in that the forming drills 2, 2′described in connection with FIGS. 3 and 9A-9B can be used as they are.

As described above, by using the taper nut of this embodiment, theworking efficiency can be improved.

Also, the female threads tapped through the taper nut can be easilyprevented from offsetting from coaxial relation to the hole of thefastened member.

Further, the fixing force to hold the taper nut in the hole can be keptconstant.

Moreover, by drilling the fastened member using the forming drill,control of the tight-fit allowance is facilitated.

It is also possible to prevent deformation of the hole 3.

In addition, the taper nut can be easily attached and detached, enablingit to be easily replaced. Therefore, the fastened member and the tapernut which are made of different materials can be discarded separatelyfrom each other.

Furthermore, the removed taper nut can be reused.

The taper nut of this embodiment is adaptable for small male screws aswell.

By employing the driving hammer according to this embodiment, it ispossible to prevent the fastened member from being damaged and tosimplify the driving operation.

By employing the automatic driving system according to this embodiment,the driving operation can also be easily automated.

A taper nut as one example of a taper implant with female threadsaccording to a second embodiment of the present invention will now bedescribed with reference to FIGS. 11 and 12. Note that the samereference numerals as in FIG. 1 denote the same portions.

A taper nut 1H as one example of the taper implant with female threadsaccording to this embodiment comprises a taper portion 101, a flangeportion 102, and female threads 104 tapped through the taper nut 1H, aswith the taper nut described above in connection with FIG. 1. Inaddition, the taper nut 1H further comprises a groove portion 105 formedat an end of the taper portion 101 on the larger-diameter side. Thegroove portion 105 is cylindrical in shape and formed in an outerperipheral surface of the taper nut 1H.

In a like manner as described above in connection with FIG. 5, the tapernut 1H is inserted into a hole bored in one fastened member by using aforming drill and then driven into the hole by using a driving hammer orthe like.

FIG. 12 shows a state that the taper nut 1H according to this embodimentis inserted into a hole 3 bored in one fastened member 4. When the tapernut 1H is dropped into the hole 3, a lower surface 103 of the flangeportion 102 is floated from a hole step portion of the hole 3. When thetaper nut 1H is driven into the hole 3 from such a condition by using ahammer or the like, forces Fa act on the fastened member 4 from thetaper nut 1H. Further, in this embodiment, the taper nut 1H includes thegroove portion 105 formed at the end of the taper nut 1H on thelarger-diameter side. Accordingly, upon the taper nut 1 being driven,forces Fb act on the groove portion 105 so that a portion of thefastened member 4 facing the groove portion 105 is elastically deformedand the thus-deformed portion engages in the groove portion 105. As aresult, the joining force between the taper nut 1H and the fastenedmember 4 can be increased as compared with the joining force obtained bythe taper nut shown in FIG. 1.

As described above, by using the taper nut of this embodiment, theworking efficiency can be improved.

Also, the joining force between the taper nut and the fastened membercan be increased. The female threads tapped through the taper nut can beeasily prevented from offsetting from coaxial relation to the hole ofthe fastened member. The fixing force to hold the taper nut in the holecan be kept constant. Deformation of the hole can be prevented.

Further, the taper nut can be easily attached and detached, enabling itto be easily replaced. Therefore, the fastened member and the taper nutwhich are made of different materials can be discarded separately fromeach other. The removed taper nut can be reused. The taper nut of thisembodiment is adaptable for small male screws as well.

A taper nut as one example of a taper implant with female threadsaccording to a third embodiment of the present invention will now bedescribed with reference to FIG. 13. Note that the same referencenumerals as in FIG. 1 denote the same portions.

A taper nut 1J as one example of the taper implant with female threadsaccording to this embodiment comprises a taper portion 101 and a flangeportion 102 as with the taper nut described above in connection withFIG. 1. But, in this embodiment, a threaded hole 106 having femalethreads 104A formed in its inner wall surface is bored as a blind hole.

In a like manner as described above in connection with FIG. 5, the tapernut 1J is inserted into a hole bored in one fastened member by using aforming drill and then driven into the hole by using a driving hammer orthe like.

Since the threaded hole 106 is not penetrating the taper nut 1J, thisembodiment is suitably employed for fastening, in particular, vacuumdevices and units. In other words, a vacuum is satisfactorily sustainedby the taper portion 101 and the flange portion 102 both held in closecontact with the hole.

As described above, by using the taper nut of this embodiment, theworking efficiency can be improved.

Also, vacuum devices and units can be easily fastened while sustaining avacuum. The female threads tapped in the taper nut can be easilyprevented from offsetting from coaxial relation to the hole of thefastened member. The fixing force to hold the taper nut in the hole canbe kept constant. Deformation of the hole can be prevented.

Further, the taper nut can be easily attached and detached, enabling itto be easily replaced. Therefore, the fastened member and the taper nutwhich are made of different materials can be discarded separately fromeach other. The removed taper nut can be reused. The taper nut of thisembodiment is adaptable for small male screws as well.

A taper nut as one example of a taper implant with female threadsaccording to a fourth embodiment of the present invention will now bedescribed with reference to FIG. 14. Note that the same referencenumerals as in FIG. 1 denote the same portions.

A taper nut 1K as one example of the taper implant with female threadsaccording to this embodiment comprises a taper portion 101, a flangeportion 102, and female threads 104 tapped in the taper nut 1K, as withthe taper nut described above in connection with FIG. 1. Further, inthis embodiment, a threaded hole having the female threads 104 iscounterbored to form a counterbored portion 107 at an end face of thetaper portion 101 on the smaller-diameter side.

The longer the threaded hole, the longer time is required to tighten amale screw. By counterboring the female threads 104 halfway like thisembodiment, the length of the threaded hole is reduced. Accordingly, themale screw can be tightened in a shorter time. From the viewpoint ofensuring the screw-fastening strength, it is desired that the remaininglength of the female threads 104 be 0.8 or more time(s) the diameter d0of the male screw.

As described above, by using the taper nut of this embodiment, theworking efficiency can be improved.

Also, a time required for tightening the male screw can be cut down. Thefemale threads tapped in the taper nut can be easily prevented fromoffsetting from coaxial relation to the hole of the fastened member. Thefixing force to hold the taper nut in the hole can be kept constant.Deformation of the hole can be prevented.

Further, the taper nut can be easily attached and detached, enabling itto be easily replaced. Therefore, the fastened member and the taper nutwhich are made of different materials can be discarded separately fromeach other. The removed taper nut can be reused. The taper nut of thisembodiment is adaptable for small male screws as well.

A taper nut as one example of a taper implant with female threadsaccording to a fifth embodiment of the present invention will now bedescribed with reference to FIG. 15. Note that the same referencenumerals as in FIG. 1 denote the same portions.

A taper nut 1L as one example of the taper implant with female threadsaccording to this embodiment comprises a taper portion 101, a flangeportion 102, and female threads 104 tapped in the taper nut 1K, as withthe taper nut described above in connection with FIG. 1. Further, inthis embodiment, a threaded hole having the female threads 104 iscounterbored to form a counterbored portion 108 at an end face of thethreaded hole on the side of the flange portion 102.

By thus counterboring the female threads 104 halfway, the length of thethreaded hole is reduced. Accordingly, the male screw can be tightenedin a shorter time. From the viewpoint of ensuring the screw-fasteningstrength, it is desired that the remaining length of the female threads104 be 0.8 or more time(s) the diameter d0 of the male screw.

As described above, by using the taper nut of this embodiment, similaradvantages to those obtainable with the taper nut shown in FIG. 14 canbe achieved.

A reference pin as one example of a taper implant with female threadsaccording to a sixth embodiment of the present invention will now bedescribed with reference to FIGS. 16 and 17. Note that the samereference numerals as in FIG. 1 denote the same portions.

As shown in FIG. 16, a reference pin 1M as one example of the taperimplant with female threads according to this embodiment comprises ataper portion 101, a flange portion 102, and female threads 104 tappedin the reference pin 1M, as with the taper nut described above inconnection with FIG. 13. Further, in this embodiment, a positioning pin109 is provided on an end face of the reference pin 1M on the side ofthe flange portion 102. The positioning pin 109 has an axis aligned withthe axis of the taper portion 101. In other words, the positioning pin109 serve as a coaxial fit portion extending in the axial direction ofthe taper portion 101.

As shown in FIG. 17, a hole 3 as described above in connection with FIG.4 is bored in a base member 4A by using a forming drill. In a likemanner as described above in connection with FIG. 5, the reference pin1M is inserted into the hole 3 bored, in the base member 4A by using aforming drill and then driven into the hole 3 by using a driving hammeror the like. The driving hammer used here has a piston so configured asto make driving force act on the flange portion 102 of the reference pin1M. Accordingly, the driving force will not act on the positioning pin109 and hence the positioning pin 109 is prevented from deforming.

The reference pin 1M is fixedly held on the base member 4A by frictionalforces between the hole 3 and the reference pin 1M driven into the hole3. The height of the positioning pin 109 can be easily specified by thepresence of the flange portion 102 of the reference pin 1M.

With engagement between the taper portion 101 of the reference pin 1Mand a hole taper portion 301 of the hole 3, the accuracy of erectness ofthe positioning pin 109 provided on the reference pin 1M can be easilyimproved.

Also, while instable reaming finish of a fit hole has been required inthe past for right erection of the positioning pin 109, this embodimentneeds no longer such reaming finish.

Further, since the reference pin 1M has the flange portion 102, it ispossible to prevent the reference pin from overly thrusting into thehole and hence prevent the hole from deforming. In addition, thereference pin 1M can be easily disengaged from the hole 3.

As described above, by using the reference pin of this embodiment, theworking efficiency can be improved.

Also, the accuracy of erectness of the positioning pin can be easilyimproved. Because the reference pin can be fixed by a bolt tightenedinto the female threads from the rear side, the force of fixing thereference pin in place can be increased. Reaming finish is no longerrequired to rightly erect the positioning pin. The fixing force to holdthe reference pin in the hole can be kept constant.

Further, the reference pin can be easily attached and detached, enablingit to be easily replaced. Therefore, the fastened member and thereference pin which are made of different materials can be discardedseparately from each other. The removed reference pin can be reused.

A taper implant with a positioning hole according to a seventhembodiment of the present invention will now be described with referenceto FIG. 18. Note that the same reference numerals as in FIG. 1 denotethe same portions.

A taper implant 1N with a positioning hole according to this embodimentis employed in pair with the reference pin 1M shown in FIG. 17. Thetaper implant 1N with a positioning hole comprises a taper portion 101and a flange portion 102 as with the taper nut described above inconnection with FIG. 1. Further, in this embodiment, a positioning hole110 is bored through the taper implant 1N. The positioning hole 110 hasan axis aligned with the axis of the taper portion 101. In other words,the positioning hole 110 serve as a coaxial fit portion extending in theaxial direction of the taper portion 101.

A hole 3 as described above in connection with FIG. 4 is bored in a basemember 4B by using a forming drill. In a like manner as described abovein connection with FIG. 5, the taper implant 1N with a positioning holeis inserted into the hole 3 bored in the base member 4B by using aforming drill and then driven into the hole 3 by using a driving hammeror the like. The taper implant 1N with a positioning hole is fixedlyheld on the base member 4B by frictional forces between the hole 3 andthe taper implant 1N driven into the hole 3.

A process for positioning two base members by using both the taperimplant with a positioning pin according to the sixth embodiment of thepresent invention and the taper implant with a positioning holeaccording to the seventh embodiment of the present invention will now bedescribed with reference to FIGS. 19A-19C.

FIG. 19A shows the same state as described above in connection with FIG.17 in which the reference pin 1M with the positioning pin 109 is driveninto the hole of the base member 4A.

FIG. 19C shows the same state as described above in connection with FIG.18 in which the taper implant 1N with the positioning hole 110 is driveninto the hole of the base member 4B.

FIG. 19B shows a state in which the base members 4A and 4B arepositioned to each other by inserting the positioning pin 109 of thereference pin 1M into the positioning hole 110 of the taper implant 1N.Such simple insertion enables both the base members 4A and 4B to bepositioned to each other.

In this respect, by boring the positioning hole 110 in the taper implant1N with high precision to form the hole having small tolerance, thepositioning accuracy between the two base members can be improved.

According to this embodiment, it is possible to easily position the twobase members.

A manner of changing tolerance of the positioning hole formed in thetaper implant with a positioning hole according to the seventhembodiment of the present invention will be described with reference toFIGS. 20A-20B.

FIG. 20A shows, by way of example, the same state as described above inconnection with FIG. 18 in which the taper implant 1N with thepositioning hole 110 is driven into the hole of the base member 4B.Here, it is assumed that the diameter of the positioning hole 110 is Dmm and the tolerance thereof is in the range of +0.02 mm to +0.03 mm. Inthe taper implant 1N of this embodiment, the taper portion of the taperimplant 1N can be easily disengaged from the hole taper portion of thehole bored in the base member 4B by hitting the end face of the taperportion on the smaller-diameter side. Further, because the taper implant1N has the flange portion, it is prevented from overly thrusting intothe hole bored in the base member 4B and hence the hole is essentiallyprevented from deforming. Accordingly, after removing the taper implant1N which has been once driven into the hole, it is easy to drive anothertaper implant into the same hole.

FIG. 20B shows, by way of example, a state that a taper implant 1N′ witha positioning hole 110A is driven into the hole of the base member 4B.Here, by employing the taper implant 1N′ wherein the diameter of thepositioning hole 110A is D mm and the tolerance thereof is in the rangeof +0.01 mm to +0.02 mm, the tolerance of the positioning hole 110 canbe easily changed. With change in the tolerance of the positioning hole110, the positioning accuracy can also be easily changed.

A reference pin as one example of a taper implant with a positioning pinaccording to an eighth embodiment of the present invention will now bedescribed with reference to FIG. 21. Note that the same referencenumerals as in FIG. 17 denote the same portions.

A reference pin 1P as one example of the taper implant with apositioning pin according to this embodiment comprises a taper portion101, a flange portion 102, female threads 104 tapped in the referencepin 1P, and a positioning pin 109, as with the reference pin describedabove in connection with FIG. 16.

After the reference pin 1P is inserted into the hole 3 bored in the basemember 4A by using a forming drill in a like manner as described abovein connection with FIG. 5, a bolt 17 is tightened into the femalethreads 104 through a washer 18 from the rear side of the base member4A. In other words, the reference pin 1P is pulled into the hole 3 bytightening the bolt 17 and, therefore, deformation of the positioningpin 109 is prevented.

Since the reference pin 1P is fixedly held on the base member 4A byfrictional forces between the hole 3 and the reference pin 1M pulledinto the hole 3 and tightening force of the bolt 17, the joiningstrength between the reference pin and the base member can be increasedas compared with the structure shown in FIG. 16.

As described above, by using the reference pin of this embodiment, theworking efficiency can be improved.

Also, the fixing force to hold the reference pin in the hole can beincreased. The accuracy of erectness of the positioning pin can beeasily improved. Reaming finish is no longer required to rightly erectthe positioning pin.

Further, the reference pin can be easily attached and detached, enablingit to be easily replaced. Therefore, the fastened member and thereference pin which are made of different materials can be discardedseparately from each other. The removed reference pin can be reused.

A reference pin as one example of a taper implant with a positioning pinaccording to a ninth embodiment of the present invention will now bedescribed with reference to FIG. 22. Note that the same referencenumerals as in FIG. 17 denote the same portions.

A reference pin 1Q as one example of the taper implant with apositioning pin according to this embodiment comprises a taper portion101 and a flange portion 102. Further, in this embodiment, a positioningpin 109 is provided at an end face of the reference pin 1Q on the sideof the flange portion 102, and a positioning pin 111 is provided at anend face of the taper portion 101 on the smaller-diameter side. Thepositioning pins 109, 111 have respective axes aligned with the axis ofthe taper portion 101. In other words, the positioning pins 109, 111each serve as a coaxial fit portion extending in the axial direction ofthe taper portion 101.

A hole 3 as described above in connection with FIG. 4 is bored in a basemember 4A by using a forming drill. In a like manner as described abovein connection with FIG. 5, the reference pin 1Q is inserted into thehole 3 bored in the base member 4A by using a forming drill and thendriven into the hole 3 by using a driving hammer or the like. Thedriving hammer used here has a piston so configured as to make drivingforce act on the flange portion 102 of the reference pin 1Q.Accordingly, the driving force will not act on the positioning pin 109and hence the positioning pin 109 is prevented from deforming.

The reference pin 1Q is fixedly held on the base member 4A by frictionalforces between the hole 3 and the reference pin 1Q driven into the hole3. The heights of the positioning pins 109, 111 are specified by thepresence of the flange portion 102 of the reference pin 1Q.

As described above, by using the reference pin of this embodiment, theworking efficiency can be improved.

Also, positioning of three base members can be easily achieved. Theaccuracy of erectness of the positioning pin can be easily improved.Reaming finish is no longer required to rightly erect the positioningpin.

Further, the reference pin can be easily attached and detached, enablingit to be easily replaced. Therefore, the fastened member and thereference pin which are made of different materials can be discardedseparately from each other. The removed reference pin can be reused.

The structure of a reference pin as one example of a taper implant witha positioning pin according to a tenth embodiment of the presentinvention will now be described with reference to FIG. 23. Note that thesame reference numerals as in FIG. 17 denote the same portions.

A reference pin 1N as one example of the taper implant with apositioning pin according to this embodiment comprises a taper portion101 and a flange portion 102 as with the reference pin described abovein connection with FIG. 16. Further, in this embodiment, a positioningpin 111 is provided at an end face of the taper portion 101 on thesmaller-diameter side.

In a like manner as described above in connection with FIG. 5, thereference pin 1N is inserted into a hole 3 bored in a base member 4A byusing a forming drill and then driven into the hole 3 by using a drivinghammer or the like. The hole 3 is drilled from the rear side of the basemember 4A. Therefore, the reference pin 1N is driven into the hole 3from the rear side of the base member 4A such that the positioning pin111 is projected outward from the front side of the base member 4A. Thisstructure makes the reference pin 1N less easily separable from the hole3.

As described above, by using the reference pin of this embodiment, theworking efficiency can be improved.

Also, the reference pin is less easily separable from the hole. Theaccuracy of erectness of the positioning pin can be easily improved.Reaming finish is no longer required to rightly erect the positioningpin.

Further, the reference pin can be easily attached and detached, enablingit to be easily replaced. Therefore, the fastened member and thereference pin which are made of different materials can be discardedseparately from each other. The removed reference pin can be reused.

The structure of a reference pin as one example of a taper implant witha positioning pin according to an eleventh embodiment of the presentinvention will now be described with reference to FIG. 24. Note that thesame reference numerals as in FIG. 17 denote the same portions.

A reference pin 1R as one example of the taper implant with apositioning pin according to this embodiment comprises a taper portion101, a flange portion 102, and a positioning pin 111 provided at an endface of the taper portion 101 on the smaller-diameter side, as with thereference pin described above in connection with FIG. 23. Further, inthis embodiment, a reference pin hole 112 is formed in an end face ofthe reference pin 1R on the side of the flange portion 102. Thereference pin hole 112 has an inner diameter allowing a positioning pin111 provided on another taper implant to be inserted to the hole 112.

In a like manner as described above in connection with FIG. 5, thereference pin 1R is inserted into a hole 3 bored in a base member 4A byusing a forming drill and then driven into the hole 3 by using a drivinghammer or the like. The hole 3 is drilled from the rear side of the basemember 4A. Therefore, the reference pin 1R is driven into the hole 3from the rear side of the base member 4A such that the positioning pin111 is projected outward from the front side of the base member 4A. Inaddition, the reference pin hole 112 of the reference pin 1R is madeopen to the rear side of the base member 4A. Accordingly, by drivinganother reference pin 1R into another base member in a like manner asshown in FIG. 24 and then inserting the positioning pin 111 of the otherreference pin 1R, which has been thus driven into the other base member,into the reference pin hole 112 of the reference pin 1R driven into thebase member 4A, the base member 4A and the other base member can beeasily positioned with respect to each other. In other words, becausethe reference pin 1R has both the positioning pin and the reference pinhole, the number of reference pins required for positioning two basemembers can be reduced.

As described above, by using the reference pin of this embodiment, theworking efficiency can be improved.

Also, the number of reference pins required for positioning two basemembers can be reduced. Since the joining strength between the referencepin and the base member is increased, they are less easily separablefrom each other. The accuracy of erectness of the positioning pin can beeasily improved. Reaming finish is no longer required to rightly erectthe positioning pin.

Further, the reference pin can be easily attached and detached, enablingit to be easily replaced. Therefore, the fastened member and thereference pin which are made of different materials can be discardedseparately from each other. The removed reference pin can be reused.

The structure of a reference pin as one example of a taper implant witha positioning pin according to a twelfth embodiment of the presentinvention will now be described with reference to FIG. 25. Note that thesame reference numerals as in FIG. 17 denote the same portions.

A reference pin 1S as one example of the taper implant with apositioning pin according to this embodiment comprises a taper portion101 and female threads 104 tapped in the taper portion 101 as with thereference pin described above in connection with FIG. 16. Further, inthe reference pin 1S of this embodiment, a positioning pin 113 having alarger diameter than the taper portion 101 is provided at an end face ofthe taper portion 101 on the larger-diameter side. Because thepositioning pin 113 has a larger diameter than the taper portion 101, alower end face 113A of the positioning pin 113 has the same function asthe lower surface 103 of the flange portion 102 of the taper nut shownin FIG. 1.

The reference pin 1S is inserted into a hole 3A bored in a base member4A by using a drill having a taper portion drilling bit and then driveninto the hole 3A by using a driving hammer or the like. The lower endface 113A of the positioning pin 113 engages the surface of the basemember 4A to thereby prevent the reference pin 1S from further thrustinginto the hole 3A. The top of the positioning pin 113 is hit by thehammer when the reference pin 1S is driven, but the positioning pin 113will not deform because it has a larger diameter than the positioningpin 109 shown in FIG. 16.

Further, a counterbored hole 19 is formed on the rear side of the basemember 4A. A bolt 17 is tightened into the female threads 104 through awasher 18 from the rear side of the base member 4A. Thus, since thereference pin 1S is fixedly held on the base member 4A by frictionalforces between the hole 3A and the reference pin 1S driven into the hole3A and tightening force of the bolt 17, the joining strength between thereference pin and the base member can be increased as compared with thestructure shown in FIG. 16. The reason of increasing the joiningstrength is to surely prevent a loosening of the reference pin 1S inview of that the reference pin 1S tends to more easily loosen becausethe positioning pin 113 has a larger diameter and is subjected to largerforce.

As described above, by using the reference pin of this embodiment, theworking efficiency can be improved.

Also, the joining strength between the reference pin and the base membercan be increased and hence they are less easily separable from eachother. The accuracy of erectness of the positioning pin can be easilyimproved. Reaming finish is no longer required to rightly erect thepositioning pin.

Further, the reference pin can be easily attached and detached, enablingit to be easily replaced. Therefore, the fastened member and thereference pin which are made of different materials can be discardedseparately from each other. The removed reference pin can be reused.

The structure of a reference pin as one example of a taper implant witha positioning pin according to a thirteenth embodiment of the presentinvention will now be described with reference to FIG. 26. Note that thesame reference numerals as in FIG. 17 denote the same portions.

A reference pin 1T as one example of the taper implant with apositioning pin according to this embodiment comprises a taper portion101 and female threads 104 tapped in the taper portion 101 as with thereference pin described above in connection with FIG. 16. Further, inthe reference pin 1T of this embodiment, a positioning pin 114 having alarger diameter than the taper portion 101 is provided at an end face ofthe taper portion 101 on the larger-diameter side. Because thepositioning pin 114 has a larger diameter than the taper portion 101, alower end face 114A of the positioning pin 114 has the same function asthe lower surface 103 of the flange portion 102 of the taper nut shownin FIG. 1. Incidentally, the diameter of the positioning pin 114 issmaller than the diameter of the positioning pin 109 shown in FIG. 25.

In a like manner as described above in connection with FIG. 5, thereference pin 1T is inserted into a hole 3 bored in a base member 4A byusing a forming drill and then driven into the hole 3 by using a drivinghammer or the like. The lower end face 114A of the positioning pin 114engages a hole step portion of the hole 3 to thereby prevent thereference pin 1T from further thrusting into the hole 3. The top of thepositioning pin 114 is hit by the hammer when the reference pin 1T isdriven, but the positioning pin 114 will not deform because it has alarger diameter than the positioning pin 109 shown in FIG. 16.

Further, a counterbored hole 19 is formed on the rear side of the basemember 4A. A bolt 17 is tightened into the female threads 104 through awasher 18 from the rear side of the base member 4A. Thus, since thereference pin 1T is fixedly held on the base member 4A by frictionalforces between the hole 3 and the reference pin 1T driven into the hole3 and tightening force of the bolt 17, the joining strength between thereference pin and the base member can be increased as compared with thestructure shown in FIG. 16. The reason of increasing the joiningstrength is to surely prevent a loosening of the reference pin 1T inview of that the reference pin 1T tends to more easily loosen becausethe positioning pin 114 has a larger diameter and is subjected to largerforce.

As described above, by using the reference pin of this embodiment,similar advantages to those obtainable with the reference pin shown inFIG. 25 can be achieved.

A taper implant with a guide bar according to a fourteenth embodiment ofthe present invention will now be described with reference to FIGS.27A-27B. Note that the same reference numerals as in FIG. 1 denote thesame portions.

As shown in FIG. 27A, a reference pin 1BB as one example of the taperimplant with a guide bar according to this embodiment comprises a taperportion 101 and female threads (not shown) tapped in the taper portion101 as with the reference pin described above in connection with FIG.16. Further, in the reference pin 1BB of this embodiment, a guide bar125 having a larger diameter than the taper portion 101 is provided atan end face of the taper portion 101 on the larger-diameter side. Theguide bar 125 has an axis aligned with the axis of the taper portion101. In other words, the guide bar 125 serve as a coaxial fit portionextending in the axial direction of the taper portion 101. Because theguide bar 125 has a larger diameter than the taper portion 101, a lowerend face 125A of the guide bar 125 has the same function as the lowersurface 103 of the flange portion 102 of the taper nut shown in FIG. 1.

On the other hand, a hole 3 is bored in a first base member 4A by usinga forming drill as described above in connection with FIG. 4. The hole 3has a hole taper portion 301 and a hole step portion 302. A counterboredhole 20 is formed at one end of the hole 3 on the rear side of the basemember 4A. Additionally, a through hole 21 into which the guide bar 125can be inserted is bored through a second base member 4B.

As shown in FIG. 27B, the reference pin 1BB is inserted into the hole 3bored in the base member 4A by using a forming drill and then driveninto the hole 3 by using a driving hammer or the like. The lower endface 125A of the guide bar 125 engages the hole step portion of the hole3 to thereby prevent the reference pin 1BB from further thrusting intothe hole 3. The top of the guide bar 125 is hit by the hammer when thereference pin 1BB is driven, but the guide bar 125 will not deformbecause it has a larger diameter than the positioning pin 109 shown inFIG. 16.

Further, a bolt 17 is tightened into the female threads in the referencepin 1BB from the rear side of the base member 4A. Thus, since thereference pin 1BB is fixedly held on the base member 4A by frictionalforces between the hole 3 and the reference pin 1BB driven into the hole3 and tightening force of the bolt 17, the joining strength between thereference pin and the base member can be increased as compared with thestructure shown in FIG. 16.

Then, the guide bar 125 of the reference pin 1BB is inserted into thethrough hole 21 of the base member 4B. Accordingly, the base member 4Bis axially slidable with respect to the base member 4A while an outerperipheral surface of the guide bar 125 serves as a sliding surface.

As described above, by using the reference pin of this embodiment, theworking efficiency can be improved.

Also, the accuracy of erectness of the positioning pin can be easilyimproved. The fixing force to hold the reference pin in the hole can bekept constant.

Further, the reference pin can be easily attached and detached, enablingit to be easily replaced. Therefore, the fastened member and thereference pin which are made of different materials can be discardedseparately from each other. The removed reference pin can be reused.

A taper implant with a tension spring post according to a fifteenthembodiment of the present invention will now be described with referenceto FIG. 28. Note that the same reference numerals as in FIG. 17 denotethe same portions.

A taper implant 1U with a tension spring post according to thisembodiment comprises a taper portion 101 and a flange portion 102 aswith the taper nut described in connection with FIG. 1. Further, in thisembodiment, a tension spring post 115 is provided at an end face of thetaper implant 1U on the side of the flange portion 102. The tensionspring post 115 has an axis aligned with the axis of the taper portion101. In other words, the tension spring post 115 serves as a coaxial fitportion extending in the axial direction of the taper portion 101. Ahole 116 for attachment of one end of a tension spring is formed in thetension spring post 115 near its distal end.

A hole 3 as described above in connection with FIG. 4 is bored in a basemember 4A by using a forming drill. In a like manner as described abovein connection with FIG. 5, the taper implant 1U with a tension springpost is inserted into the hole 3 bored in the base member 4A by using aforming drill and then driven into the hole 3 by using a driving hammeror the like. The driving hammer used here has a piston so configured asto make driving force act on the flange portion 102 of the taper implant1U with a tension spring post. Accordingly, the driving force will notact on the tension spring post 115 and hence the tension spring post 115is prevented from deforming.

The taper implant 1U with a tension spring post is fixedly held on thebase member 4A by frictional forces between the hole 3 and the taperimplant 1U driven into the hole 3. The height of the tension spring post115 is specified by the presence of the flange portion 102 of the taperimplant 1U with a tension spring post.

By attaching one end of the tension spring to the hole 116, the tensionspring can be fixed to the post 115 at one end thereof.

As described above, by using the taper implant of this embodiment, theworking efficiency can be improved.

Further, the taper implant can be easily attached and detached, enablingit to be easily replaced. Therefore, the fastened member and the taperimplant which are made of different materials can be discardedseparately from each other. The removed taper implant can be reused.

A taper implant with a tension spring post according to a sixteenthembodiment of the present invention will now be described with referenceto FIG. 29. Note that the same reference numerals as in FIG. 17 denotethe same portions.

A taper implant 1V with a tension spring post according to thisembodiment comprises a taper portion 101 and a flange portion 102 aswith the taper implant described in connection with FIG. 23. Further, inthis embodiment, a tension spring post 115 having a hole 116 formedtherein is provided at an end face of the taper portion 101 of the taperimplant 1V on the smaller-diameter side.

A hole 3 as described above in connection with FIG. 4 is bored in a basemember 4A by using a forming drill. In a like manner as described abovein connection with FIG. 5, the taper implant 1V with a tension springpost is inserted into the hole 3 bored in the base member 4A by using aforming drill and then driven into the hole 3 by using a driving hammeror the like. The hole 3 is drilled from the rear side of the base member4A. Therefore, the taper implant 1V is driven into the hole 3 from therear side of the base member 4A such that the tension spring post 115 isprojected outward from the front side of the base member 4A.

The taper implant 1V with a tension spring post is fixedly held on thebase member 4A by frictional forces between the hole 3 and the taperimplant 1V driven into the hole 3. By attaching one end of the tensionspring to the hole 116, the tension spring can be fixed to the post 115at one end thereof. Since the force imposed on the taper implant 1V fromthe tension spring acts in a direction to further tighten a fit betweenthe taper implant 1V and the base member 4A, the taper implant 1V ismore surely prevented from loosening.

As described above, by using the taper implant of this embodiment, theworking efficiency can be improved.

Also, the joining strength between the taper implant and the base membercan be increased and hence they are less easily separable from eachother.

Further, the taper implant can be easily attached and detached, enablingit to be easily replaced. Therefore, the fastened member and the taperimplant which are made of different materials can be discardedseparately from each other. The removed taper implant can be reused.

A taper implant with a tension spring post according to a seventeenthembodiment of the present invention will now be described with referenceto FIG. 30. Note that the same reference numerals as in FIG. 17 denotethe same portions.

A taper implant 1W with a tension spring post according to thisembodiment comprises a taper portion 101 and a flange portion 102 aswith the taper implant described in connection with FIG. 28. Further, inthis embodiment, a tension spring post 117 is provided at an end face ofthe taper implant 1W on the side of the flange portion 102. The tensionspring post 117 has an axis aligned with the axis of the taper portion101. In other words, the tension spring post 117 serves as a coaxial fitportion extending in the axial direction of the taper portion 101. Ahole 118 for attachment of one end of a tension spring is formed in thetension spring post 115 near its distal end.

A hole 3 as described above in connection with FIG. 4 is bored in a basemember 4A by using a forming drill. In a like manner as described abovein connection with FIG. 5, the taper implant 1U with a tension springpost is inserted into the hole 3 bored in the base member 4A by using aforming drill and then driven into the hole 3 by using a driving hammeror the like. The driving hammer used here has a piston so configured asto make driving force act on the flange portion 102 of the taper implant1U with a tension spring post. Accordingly, the driving force will notact on the tension spring post 117 and hence the tension spring post 117is prevented from deforming.

The taper implant 1W with a tension spring post is fixedly held on thebase member 4A by frictional forces between the hole 3 and the taperimplant 1W driven into the hole 3. The height of the tension spring post117 is specified by the presence of the flange portion 102 of the taperimplant 1W with a tension spring post.

By attaching one end of the tension spring to the groove 118, thetension spring can be fixed to the post 117 at one end thereof.

As described above, by using the taper implant of this embodiment, theworking efficiency can be improved.

Further, the taper implant can be easily attached and detached, enablingit to be easily replaced. Therefore, the fastened member and the taperimplant which are made of different materials can be discardedseparately from each other. The removed taper implant can be reused.

A taper implant with a tension spring post according to an eighteenthembodiment of the present invention will now be described with referenceto FIG. 31. Note that the same reference numerals as in FIG. 17 denotethe same portions.

A taper implant 1X with a tension spring post according to thisembodiment comprises a taper portion 101 and a flange portion 102 aswith the taper implant described in connection with FIG. 23. Further, inthis embodiment, a tension spring post 117 having a groove 118 formedtherein is provided at an end face of the taper portion 101 of the taperimplant 1X on the smaller-diameter side.

A hole 3 as described above in connection with FIG. 4 is bored in a basemember 4A by using a forming drill. In a like manner as described abovein connection with FIG. 5, the taper implant 1X with a tension springpost is inserted into the hole 3 bored in the base member 4A by using aforming drill and then driven into the hole 3 by using a driving hammeror the like. The hole 3 is drilled from the rear side of the base member4A. Therefore, the taper implant 1X is driven into the hole 3 from therear side of the base member 4A such that the tension spring post 117 isprojected outward from the front side of the base member 4A.

The taper implant 1X with a tension spring post is fixedly held on thebase member 4A by frictional forces between the hole 3 and the taperimplant 1X driven into the hole 3. By attaching one end of the tensionspring to the groove 118, the tension spring can be fixed to the post117 at one end thereof. Since the force imposed on the taper implant 1Xfrom the tension spring acts in a direction to further tighten a fitbetween the taper implant 1X and the base member 4A, the taper implant1X is more surely prevented from loosening.

As described above, by using the taper implant of this embodiment, theworking efficiency can be improved.

Also, the joining strength between the taper implant and the base membercan be increased and hence they are less easily separable from eachother.

Further, the taper implant can be easily attached and detached, enablingit to be easily replaced. Therefore, the fastened member and the taperimplant which are made of different materials can be discardedseparately from each other. The removed taper implant can be reused.

A taper implant with a bearing post according to a nineteenth embodimentof the present invention will now be described with reference to FIG.32. Note that the same reference numerals as in FIG. 17 denote the sameportions.

A taper implant 1Y with a bearing post according to this embodimentcomprises a taper portion 101 and a flange portion 102 as with the taperimplant described in connection with FIG. 28. Further, in thisembodiment, a bearing post 119 is provided at an end face of the taperimplant 1Y on the side of the flange portion 102. The bearing post 119has an axis aligned with the axis of the taper portion 101. In otherwords, the bearing post 119 serves as a coaxial fit portion extending inthe axial direction of the taper portion 101.

A hole 3 as described above in connection with FIG. 4 is bored in a basemember 4A by using a forming drill. In a like manner as described abovein connection with FIG. 5, the taper implant 1Y with a bearing post isinserted into the hole 3 bored in the base member 4A by using a formingdrill and then driven into the hole 3 by using a driving hammer or thelike. The driving hammer used here has a piston so configured as to makedriving force act on the flange portion 102 of the taper implant 1Y witha bearing post. Accordingly, the driving force will not act on thebearing post 119 and hence the bearing post 119 prevented fromdeforming.

The taper implant 1Y with a bearing post is fixedly held on the basemember 4A by frictional forces between the hole 3 and the taper implant1Y driven into the hole 3. The height of the bearing post 119 isspecified by the presence of the flange portion 102 of the taper implant1Y with a bearing post.

After driving the taper implant 1Y into the base member 4A, a ballbearing 120 is fitted over the post 119 from its top. Then, by placing acollar 121 on the ball bearing 120 and inserting a snap ring 122 into agroove defined between the collar 121 and the post 119, the ball bearing120 is fixed to the post 119. Incidentally, the bearing 120 is notlimited to a ball bearing, but may be a roll bearing.

As described above, by using the taper implant of this embodiment, theworking efficiency can be improved.

Further, the taper implant can be easily attached and detached, enablingit to be easily replaced. Therefore, the taper implant of thisembodiment is suitably employed under situations where the bearing tendsto be much damaged. In addition, the fastened member and the taperimplant which are made of different materials can be discardedseparately from each other. The removed taper implant can be reused.

A taper implant with a bearing post according to a twentieth embodimentof the present invention will now be described with reference to FIG.33. Note that the same reference numerals as in FIG. 17 denote the sameportions.

A taper implant 1Z with a bearing post according to this embodimentcomprises a taper portion 101 and a flange portion 102 as with the taperimplant described in connection with FIG. 32. Further, in thisembodiment, a bearing post 119 is provided at an end face of the taperportion 101 of the taper implant 1Z on the smaller-diameter side.

A hole 3 as described above in connection with FIG. 4 is bored in a basemember 4A by using a forming drill. In a like manner as described abovein connection with FIG. 5, the taper implant 1Z with a bearing post isinserted into the hole 3 bored in the base member 4A by using a formingdrill and then driven into the hole 3 by using a driving hammer or thelike. The hole 3 is drilled from the rear side of the base member 4A.Therefore, the taper implant 1Z is driven into the hole 3 from the rearside of the base member 4A such that the bearing post 119 is projectedoutward from the front side of the base member 4A.

After driving the taper implant 1Z into the base member 4A, a ballbearing 120 is fitted over the post 119 from its top. Then, by placing acollar 121 on the ball bearing 120 and inserting a snap ring 122 into agroove defined between the collar 121 and the post 119, the ball bearing120 is fixed to the post 119. Incidentally, the bearing 120 is notlimited to a ball bearing, but may be a roll bearing.

The taper implant 1Z with a bearing post is fixedly held on the basemember 4A by frictional forces between the hole 3 and the taper implant1Z driven into the hole 3. Since the force imposed on the taper implant1Z from the bearing acts in a direction to further tighten a fit betweenthe taper implant 1Z and the base member 4A, the taper implant 1Z ismore surely prevented from loosening.

As described above, by using the taper implant of this embodiment, theworking efficiency can be improved.

Also, the joining strength between the taper implant and the base membercan be increased and hence they are less easily separable from eachother.

Further, the taper implant can be easily attached and detached, enablingit to be easily replaced. Therefore, the fastened member and the taperimplant which are made of different materials can be discardedseparately from each other. The removed taper implant can be reused.

A taper implant with a stud bolt according to a twenty-first embodimentof the present invention will now be described with reference to FIG.34. Note that the same reference numerals as in FIG. 17 denote the sameportions.

A taper implant 1AA with a stud bolt according to this embodimentcomprises a taper portion 101 and a flange portion 102 as with the taperimplant described in connection with FIG. 29. Further, in thisembodiment, a stud bolt 123 is provided at an end face of the taperportion 101 of the taper implant 1AA on the smaller-diameter side. Thestud bolt 123 has male threads 124 tapped near its tip.

A hole 3 as described above in connection with FIG. 4 is bored in a basemember 4A by using a forming drill. In a like manner as described abovein connection with FIG. 5, the taper implant 1AA with a stud bolt isinserted into the hole 3 bored in the base member 4A by using a formingdrill and then driven into the hole 3 by using a driving hammer or thelike. The hole 3 is drilled from the rear side of the base member 4A.Therefore, the taper implant 1AA is driven into the hole 3 from the rearside of the base member 4A such that the stud bolt 123 is projectedoutward from the front side of the base member 4A.

The taper implant 1AA with a stud bolt is fixedly held on the basemember 4A by frictional forces between the hole 3 and the taper implant1AA driven into the hole 3. Since the force imposed on the taper implant1AA from a member fixed to the stud bolt 123 through the male threads124 acts in a direction to further tighten a fit between the taperimplant 1AA and the base member 4A, the taper implant 1AA is more surelyprevented from loosening.

While the tamper implant 1AA is driven into the hole 3 from the rearside of the base member 4A in the illustrated embodiment, it may bemodified to be driven from the front side of the base member 4A like thetaper implant of FIG. 27 corresponding to the taper implant of FIG. 28.

As described above, by using the taper implant of this embodiment, theworking efficiency can be improved.

Also, the joining strength between the taper implant and the base membercan be increased and hence they are less easily separable from eachother.

Further, the taper implant can be easily attached and detached, enablingit to be easily replaced. Therefore, the fastened member and the taperimplant which are made of different materials can be discardedseparately from each other. The removed taper implant can be reused.

According to the present invention, a taper implant including an axiallyextending member can be attached to a base member with higher workingefficiency.

By using a taper implant with female threads, the screw-fasteningstructure can be simplified.

By using a forming drill, control of the tight-fit allowance of thetaper implant can be easily achieved.

In addition, by using a hammer for driving the taper implant, damage ofthe base member can be prevented.

What is claimed is:
 1. A fastener structure for fastening a first memberand a second member by using a taper implant and a threaded connection,said taper implant comprising: a taper portion being frusto-conical inshape whereby said taper portion has a larger diameter end having afirst diameter and a smaller diameter end having a second diameter whichis smaller than said first diameter; a projecting portion formed at saidlarger diameter end and projecting in a direction perpendicular to adirection of an axis of said taper portion; a first hole opened at saidsmaller diameter end of said taper portion and extending in a directionof an axis of said taper portion; and a female thread formed in a wallof said first hole; a second hole formed passing through said firstmember, said second hole including; a hole step portion for opening at asurface of said first member, having a third diameter which is largerthan a diameter of said projecting portion of said taper implant, andhaving a columnar shape; a tapered hole portion frusto-conical in shape,and having an enlarged opening portion having a fourth diameter smallerthan said third diameter and a reduced opening portion having a fifthdiameter smaller than said fourth diameter, wherein a value of a taperof said tapered hole portion is the same as a value of a taper of saidtaper portion; said first member further comprising a step portionlocated at a bottom of said hole step portion, and having a circularface perpendicular with an axis of said second hole, wherein saidenlarged opening portion of said tapered hole portion is opened at saidstep portion; wherein said fourth diameter is smaller than said firstdiameter, and a tight-fit allowance when said taper portion of saidtaper implant is inserted into said tapered hole portion of said secondhole is 2-20% of said first diameter, and said taper implant beinginserted into said second hole of said first member from said smallerdiameter end of said taper portion, a side surface of said taper portionbeing in contact with a surface of a wall of said tapered hole portion,a lower face of said projecting portion being in contact with said faceof said step portion, and said taper implant being fixed in said secondhole by a friction force generated between said side surface of saidtaper portion and said surface of said wall portion of said tapered holeportion; a third hole formed in said second member, arranged so as to beopposed to a face which is opposite to said surface at which said holestep portion of said first member is opened; and a bolt inserted intosaid second hole of said first member through said third hole of saidsecond member when said first member is fastened with said second memberby fastening a male thread portion of said bolt with said female threadof said taper implant.
 2. A fastener structure according to claim 1,wherein said taper implant is fabricated of materials having a similarhardness with said first member or materials harder than said firstmember.
 3. A fastener structure according to claim 1, wherein a-saidfirst diameter d1 of said larger diameter end of said taper portion ofsaid taper implant is 1.1-2 times a diameter d0 of said bolt, a diameterd2 of said projecting portion is d0+(0.5 mm to 3 mm), a thickness t ofsaid projecting portion is 0.5 mm to 3 mm, and a length L of said taperimplant is d0×(1 to 3).
 4. A fastener structure according to claim 1,wherein said value of said taper of said tapered hole portion of saidsecond hole and said value of said taper of said taper portion of saidtaper implant are both 1/50-1/6.
 5. A fastener structure according toclaim 1, wherein said side surface of said taper portion of said taperimplant is smooth and uniform, and said lower face of said projectingportion is constructed so as not to get into said second hole when saidtaper implant is inserted into said second hole.
 6. A fastener structureaccording to claim 2, wherein said taper implant is fabricated of amaterial selected from a stainless steel, an aluminum, a SS steel, acarbon steel, a light alloy steel, a tempered steel hardened andannealed at a HRC 15 to 25 degrees, a phosphor bronze, a brass or aplastic material.
 7. A fastener structure for fastening two members by athreaded connection, comprising: a taper implant, said taper implantincluding: a taper portion being frusto-conical in shape whereby saidtaper portion has a larger diameter end having a first diameter and asmaller diameter end having a second diameter which is smaller than saidfirst diameter; a projecting portion formed circularly at said largerdiameter end so as to project from a side surface of said taper portion;a first hole opened at said smaller diameter end of said taper portionand extending in a direction of an axis of said taper portion; and afemale thread formed in a wall of said first hole; a first member beingformed with a second hole passing through said first member, said secondhole including; a hole step portion for opening at a surface of saidfirst member, and having a third diameter which is larger than adiameter of said projecting portion of said taper implant, and having acolumnar shape; a hole tapered portion having a frusto-conical shape ina direction of a center axis, and having an enlarged opening portionhaving a fourth diameter smaller than said third diameter and a reducedopening portion having a fifth diameter smaller than said fourthdiameter, wherein a taper rate of said hole tapered portion is the sameas a taper rate of said taper portion; and wherein said fourth diameteris smaller than said first diameter, and a tight-fit allowance when saidtaper portion of said taper implant is inserted into said hole taperedportion of said second hole is 2-20% of said first diameter, said firstmember further comprising a step portion located at a bottom of saidhole step portion, and having a circular face being substantiallyperpendicular with an axis of said second hole, wherein said enlargedopening portion of said hole tapered portion is opened at said stepportion; said taper implant being inserted into said second hole so thatsaid side surface of said taper portion is in contact with a surface ofa wall of said hole tapered portion, a lower face of said projectingportion is in contact with said face of said step portion, and saidtaper implant is fixed in said second hole by a friction force generatedbetween said side surface of said taper portion and said surface of saidwall of said hole tapered portion; a second member being arranged so asto be opposed to a surface-which is opposite to said surface opening ofsaid hole step portion of said first member; and a bolt having a malethread portion at one end, and being inserted into said second hole ofsaid first member so as to project from a face of said second memberopposing said first member; and wherein said bolt is inserted from saidsmaller diameter end of said taper portion of said taper implant intosaid first hole, said first member is fastened with said second memberby fastening said male thread portion of said bolt with said femalethread of said taper implant.
 8. A fastener structure according to claim7, wherein said first hole is a non-passing through-hole and is openedat said smaller diameter end of said taper portion.
 9. A fastenerstructure according to claim 7, wherein said taper rate of said holetapered portion of said second hole and said taper rate of said taperportion of said taper implant are both 1/50-1/6.
 10. A fastenerstructure according to claim 7, wherein said taper implant is fabricatedof materials having a similar hardness with said first member ormaterials harder than said first member.
 11. A fastener structureaccording to claim 10, wherein said taper implant is fabricated of amaterial selected from a stainless steel, an aluminum, a SS steel, acarbon steel, a light alloy steel, a tempered steel hardened andannealed at a HRC 15 to 25 degrees, a phosphor bronze, a brass or aplastic material.
 12. A fastener structure according to claim whereinsaid first diameter d1 of said larger diameter end of said taper portionof said taper implant is 1.1.-2 times a diameter d0 of said bolt, saiddiameter d2 of said projecting portion is d0+(0.5 mm to 3 mm), athickness t of said projecting portion is 0.5 mm to 3 and a length L ofsaid taper implant is d0×(1 to 3).
 13. A fastener structure forfastening two members by a threaded connection, comprising: a taperimplant, said taper implant including: a taper portion frusto-conical inshape whereby said taper portion has a larger diameter end having afirst diameter and a smaller diameter end having a second diameter whichis smaller than said first diameter; a projecting portion formedcircularly at said larger diameter end so as to project from a sidesurface of said taper portion; a bolt portion formed at a smallerdiameter end of said taper portion, and being formed so as to projectfrom said taper portion in a direction of an axis of said taper portion,and wherein a male thread is formed at an end of said bolt portion; afirst member being formed with a first hole passing there through, saidfirst hole including; a hole step portion for opening at a surface ofsaid first member, having a third diameter which is larger than adiameter of said projecting portion of said taper implant, and having acolumnar shape; a hole tapered portion having a frusto-conical shape ina direction of a center axis, and having an enlarged opening portionhaving a fourth diameter smaller than said third diameter and a reducedopening portion having a fifth diameter smaller than said fourthdiameter, wherein a taper rate of said hole tapered portion is as thesame as a taper rate of said taper portion; wherein said fourth diameteris smaller than said first diameter, and a tight-fit allowance when saidtaper portion of said taper implant is inserted into said hole taperedportion of said first hole is 2-20% of said first diameter, said firstmember further comprising a step portion locating at a bottom of saidhole step portion, and having a circular face substantiallyperpendicular with an axis of said first hole, wherein said enlargedopening portion of said hole tapered portion is opened at said stepportion; a second member being arranged opposed to a surf ace which isopposite to said surface at which said hole step portion of said firstmember is opened; and wherein a second hole is formed in said secondmember, and arranged opposed to said first member, and a female threadis formed in a wall of said second hole; said taper implant beinginserted into said first passing-through hole so that said side surfaceof said taper portion is in contact with a surface of a wall of saidhole tapered portion, a lower face of said projecting portion is incontact with said face of said step portion, and said taper implant isfixed in said first hole by a friction force generated between said sidesurface of said taper portion and said surface of said wall of said holetapered portion; and wherein said bolt portion which is projected fromsaid first hole of said first member is inserted in said second hole ofsaid second member, said first member being fastened with said secondmember by fastening said male thread of said bolt portion with saidfemale thread of said second hole.
 14. A fastener structure according toclaim 3, wherein said taper implant is fabricated of materials having asimilar hardness with said first member or materials harder than saidfirst member.
 15. A fastener structure according to claim 14, whereinsaid taper implant is fabricated of a material selected from a stainlesssteel, an aluminum, a SS steel, a carbon steel, a light alloy steel, atempered steel hardened and annealed at a HRC 15 to 25 degrees, aphosphor bronze, a brass or a plastic material.
 16. A fastener structureaccording to claim 13, wherein said taper rate of said hole taperedportion of said first hole and said taper rate of said taper portion ofsaid taper implant are both 1/50-1/6.
 17. A fastener structure accordingto claim 13, wherein said side surface of said taper portion of saidtaper implant is smooth and uniform, and said lower face of saidprojecting portion is constructed so as not to get into said first-holewhen said taper implant is inserted into said first hole.